Milling cutter



July 10,51928. l

' O. VONEBERHARD MILLING CUTTERl Filed July 20, 1926v 2 Sheets-Sheet l hij N m Mmm] 'l' v O. VON EBERHARD v MILLING CUTTER l Filecji July 20, 1926 'July lo, ma

2 Sheets-Sheet 2 Patented 'Jury 10, 192e.-

,limpian stares OTTO VON BERHBD, 0F ESSEN, GERMANY, AISSIGNOB T0 FRIED. KRUPI? AKTIENG-l- SELLSCEAFT, OF ESSEN-ON-THE-RUHR, GERMANY.

MILLING CUTTER.

Application led July 20, 1926, Serial No. 123,673, and in Germany January 30, 1926.

The invention relates to milling cutters of the kind described in my pending'l patent application dated November 9th, 1925, Serial Number 67,924, and has iii particular refer- 5 ence to those milling cutters which are lcomposed of individual disks and with which the conditions are so chosen that by altering the mutual arrangement of said disks the cutting teeth arranged along quick motion l helical lines inclined to'one side, as well as those arranged along helical lines. inclined to the other side may bey brought into comi mon ranks or lines. The object of my present invention is a milling cutter of the above-a stated kind, in which the alteration of the mutual arrangement of the disks is eifected by turning them.

Two cylindrical worm hobs are illustrated as embodiments of my invention in the drawings which accompany and form part of this specication, these embodiments further offering the advantage that the individual coils of the worms have the same mutual spacing over the entire length of the hob after turn! ing'the said disks, as before, so that a regrinding of the flanks of the teeth is rendered ossiblel in an easy manner even after the dis have been turned.

In the drawings: M Y.

Fig. l shows the developed shell surface of the milling cutter forming the :[irst embodiment,

. Figs. 2 and 3 show each a development of the same milling cutter with the individuali disks in altered angular positions;

Fig. 4 shows the second embodiment in a view corresponding to Fig. 1, and

Fig. 5 shows the same" in a view corresponding to Fig. 3.

The embodiment illustrated in Figs. 1 to 3 will be described rst. The milling cutter is composed of six disks A to F which are mounted, in the manner described in my prior application, on. a

sleeve-shaped carrier (not shown), and are secured thereon against lon 'tudinal and turning movement, this latter eing prevent- -ed by a spline of the carrier engaging corresponding longitudinal grooves of the disks A to F. Disk A has but one groove, a1,whil e the disks B to F have two grooves each, viz',

h1, b2, c1, c2, d?, d2,' e1, e2, f1, f2, respectively.

in Fig. 1 the disks A to F take a mutual "angular position in which the individual coils of the. worm thread, denoted by the dot and dash straight lines a2, b3, c3, d3, c3, f3, everywhere have the same mutual distance even over the joint between two neighboring disks. The teeth of the milling cutter are arranged in longitudinal rows at equal angular dlstances and on quick motion helical lines and, in particular, the teeth a3, b4, c4, d4, e, f4, which extend along helical lines inclined to the right, are located in common ranks, while the teeth a4, b5, c5, d5, e, f5 follow each other in zig-zag lines. Further- -morekwiththe described mutual arrangement of the disks A to F the spline of the carrler engages the grooves a1, b1, c1, d1, e1,

flvof the disks. With the disks in this posi-v tion the teeth a3, b4, c4, d?, e4, f4 can be round without diiiiculty at their front aces as well as at their backed-od flanges.

As shown in Fig. 2, by an alteration of the mutual angular position of the disks A to F, that is by turning them, it is easily attained that now the teeth @4,55, c5, d, e?, f5 come to be located in common ranks, this oering the possibility of easily grinding` the front faces of these teeth'. rihis turning of the dlsks, however, causes the distance between two nelgliboring worm coils (for instance/a2 andb V'of neighboring disks, to

change, as can e seen from Fig. 2, and

`in this case the individual coils would no longer be equally spaced over the entire length of the cutter, this rendering much `more dicult the grinding of the teeth ianks. Fig. 3 shows the manner in which this drawback may beobviate'd.

ln the position of the disks illustrated in Fig. 2 they have been turned in a direction such as to cause the distance between neighboring coils of neighboring disks to have diminished. Now, when the disks are shifted from the position'of Fig. v2 in the oblique longitudinal direction indicated by arrow ai, that is, the direction along which the 'ont faces of a row of teeth inclined to nthe left lie, to such an extent that the spacing of the coils located near the jointsl between two neighboring disks is again uniform,l as in the position of Fig. 1., thenV the arrangement illustrated in Fig. 3 will be attained. ,Of course, the front faces of the teeth' alt, h5 5 continue to lie in their common rank, upon said longitudinal displacement tahng place. The correct mutual distance of the ariane esv disks A to F, when in position of Fig. 3, is

secured by suitable rings G interposed bea parallel shifting motion in the direction' tween them. Of course, in reality the described displacement of the disks A to .F does not consist, as inthe development, 1n

` by acertain amount from t at of Fig. 2,

g hob shown in these .due to said oblique shifting motion in the direction of arrow w. The disks may thus be fastened on the carrier in this angular position and with distances determined-by the interposed rings G. In this position also the teeth a?, b5 f5, located along the helical lines inclined to the left are adapted to be ground on their front faces as well as on the flanks, since not only the front faces lie in common ranks, but also the flanks follow each other at equal distances over the whole length of the cutter. For the milling work the disks A to F are brought again into their position of Fig. 1.

Figs. 4 and 5 demonstrate that under certain circumstances the ,intermediate rings G may be dispensed with, namely, when the worm hob has multi le helical thread. The guresis assumed to be composed of'three disks H, J, K and has triple thread, the pitch of which is equal to the thickness of the disks. The individual coils of said three threads of disk H are denoted by k1, h2, ha, of disk J by i1, i2, 3, of disk K by k1, k2, k3. In Fig. 4 the disks H, J, K are shown in a mutual angular position, in which the teeth h4, i* and k, located on the helical lines inclined to the right lie in common ranks, while the teeth inclined to the left, It, 5 and 705- follow each other in zig-zag lines, the teeth being arranged in eight longitudinal rows along luick motion helical lines and at equal angu ar distances lw. Of the coils of the worm thread located on two neighboring disks the coils k2 and i2, h3 andia, 2 and k2 and i3 and 7c3 lie -in a common rank. If, now, the mutual angular position ofthe disks is thought to be altered, in the manner shown in Fig. 5, by the angular distance W1=120 between two neighboring disks, then the coils h1 and i2, h2 and 3, 71,3 and i1, l and k2, 2 and k3 and 3 and k1,

.whichpreviously were located at different ranks, come to lie in common ranks, so that the'individual kcoils have equal spacing again over the entire length of the worm hob, wlthout it being necessary, as in the first embodiment, to interpose rings G. By'

.suitably adaptin the conditions it may easily be attained tat by turning the disks an angle W1 the teeth h, i5, k, located on the helical lines inclined to the left, come into -angle w24-low, beingy 0 or any integral number. In thepresent case, as the worm hob has eight rows of l'teeth of each inclinat0 lah/10# 30. If, further, k is taken :2, the required turning angle becomes w2+kw=3o+a45b=1gzol As this angle is =W it results that when the disks are turned according'to the angular distance (W1) of the individual helical threads, the teeth h5, 5, los at the same time come to lic in a common rank, as Fig. 5 shows.

In order to secure the disks in their different mutual angular positions a longitudinal groove he is provided in disk H, two" grooves z', i7 in disk J andtwo grooves lli, klein disk K, these grooves corresponding tothe grooves a1, b1, c1 f1 of the first embodiment.

Instead of turning the disks the angle W,=120, they may of course be turned double this angle 2W,=240, as, in this case .too all the coils located on different disks of the worm thread come to lie in common ranks. By suitably selecting the special conditions it may easily be attained, in this case too that,n upon turning the disks 2W1=240,

i the teeth previously extending in a zig-zag line come into common ranks. The essential point merely consist in that the turning angle is in a. proportion of an integral -number to the angular distance (W1) of neighborin helical threads. The same object may attained with any' other multlple thread instead of triple thread by suitable selection of measurements in accordance with the principles set forth in connection with the illustrative embodiment described. In the foregoing specification I explained my invention, for the sake of simplicity, as

adapted to a milling cutter of cylindrical shape, in which the developed .surfaces are of rectangular shape. "-The given explanations, however, include mutatis mutandis such as milling cutters of conical shape, the developments of which have the shape of annular sectors. With conical milling cutters my invention is of a particular importance, because the alterations ofthe arrangement of the individual disks of conical cutters can be effected lonly by turning them, whilst with cylindrical cutters this alteration may be effected, besides, in the mana pluraltwo series of teeth on said disks,

one series being arranged along quick mo-V tion helical lines inclined to the right, the other series being arranged along quick motion helical lines inclined to the left, the lines of one series being broken at the joints between two disks toy form zig-zag rows of teeth when the teeth of the other series are arranged in common ranks along all the disks, and means each other, in one of which the teeth lof one series are aI'ran' ed in common ranks, an in the other of which the teeth of the other series are arranged in common ranks.

2. A millingv cutter according to claim 1 in which the teeth of both series. are arranged along screw 'thread lines, the threads being equally spaced along the whole length of the cutter when the disks are 1n one relative position, and means for holding the disks a denite distance apart in the other relative position thereof, the distance being such as to maintain the spacing of the for holding'the disks in two diierent angular positions relative to threads. uniform in the second mentioned relative position.

3. In a milling cutter according to claim 1 in which the teeth of both series are arranged along screw thread lnes, the threads being equally spaced alon the whole length of the cutter when the disis are in one relative position, and a washer for each two neighboring disks, said washer being adapted to be inserted between the d disks to hol them a definite distance apart in the other relative position thereof, said distance being such as to maintain the spacing of the threads uniform in the second relative position.

4. A milling cutter according 4to claim 1 in which the' teeth of both series are arranged along multiple screw thread lines, the angular distance between the two relative positions of the disks being in the proportion of an integral number to the angulnentioned lar distance between neighboring screw threads measured in a plane perpendicular to the axis of the cutter.4

The foregoing speciiicatlon signed at Cologne, Germany, this 1st day of July, 1926.

OTTO v. EBERHARD. 

